Teaching neuroimages: Resolution of MRI abnormalities in megalencephalic leukoencephalopathy with subcortical cysts.

Abstract

A boy was diagnosed at age 10 months with megalencephalic leukoencephalopathy with subcortical cysts (MLC) based on progressive macrocephaly and characteristic MRI findings (figure, A–C).¹ Over subsequent years, initial motor delays resolved and neurobehavioral difficulties were mild. On repeat MRI at 6 years (figure, D–F), only small areas of frontal and temporal white matter signal alteration remained, consistent with remitting MLC (MLC2b). MLC2b is associated with heterozygous mutations in <i>HEPACAM</i> with autosomal dominant inheritance. Often, one parent has macrocephaly.¹ Unlike the more common phenotype seen with <i>MLC1</i> mutations, MLC2b patients demonstrate remarkable MRI improvement and have a better clinical prognosis.²